| This paper choose with uranium-producing rock mass, which is the Jiling compound granite rock mass as the research object in the middle Longshou mountains, we have systematically summarized the characteristics of Jiling compound granite rock mass, which has based on field geological investigation, petrography, mineralogy, geochemistry and Sr-Nd-Pb isotope research. Finally, we have deeply discussed granite material sources and the magma evolution’s process, as well as the relationships between granite magmatism and uranium mineralization.Through field geological survey, project team and previous data, basically found that the Paleozoic granite in the middle Longshou Moutains areas is a complex massif(Jiling compound rock mass), are mainly distributed in Yushigou, Jiling, Xinshuijing areas, controlled by the Malugou fracture, in the form of long strip or island output. including the early Paleozoic for the first time late intrusion(lithology is mainly for gray medium-fine grained monzonitic granite); the early Paleozoic second late intrusion( pink medium-coarse grained monzonitic granite); late Paleozoic early intrusion( pink fine grained granites and fine grained potassium feldspar granite).Compound granite rock mass is consist of different period time rock, with the characteristics of low silicon, low potassium, high sodium, Enrichment in ALK(K2O+ Na2O), medium differentiation index DI value, A/CNK are less than 1.1( belong to aluminum) and calcium alkaline-alkaline series; being similar with spider diagram of trace element and rare earth distribution patterns, enrichment in LREE, LILE(U, Pb) and REE( La, Nd), relative enrichment in Th and HFSE(Zr and Hf), yet loss of Rb, Nb, Eu, Sr, Ti, P, Ba, Ta and δEu negative anomaly(respectively mean of δEu.in 0.65, 0.6, 0.514),with granite rock of U and Th content is high. The compositions of isotope of granite of(87Sr/86Sr)i values are within a range between the continental crust; from the early to the late, the average of initial Sr isotope ratios(87Sr/86Sr)i has a characteristics of rising before reducing, and the average of εNd(t) increases after the first drop, as well as T2 DM average is 2030 Ma, 1814.66 Ma and 1737.5 Ma respectively, which is very close to the age of residual crust. Pb isotope ratios are high, μ values range from 9.36 to 9.49, with an average of 9.41, all samples showed a high radioactive causes Pb isotopic characteristic with a mixed source.It is showed that the Paleozoic granite(Jiling compound granite rock mass) formation of causes belong to the I-type granites in the Middle Longshou mountains, with post-collision tectonic environment of late early Paleozoic, late Paleozoic early Mesozoic magmatism. The Paleozoic granite magma source area is mainly from the Paleoproterozoic Longshou mountain Group of residues of crustal material melting, the secondly, is the Proterozoic Dunzigou Group of the crustal material, at the same time, there are mixed with a small amount of mantle source material, accompanied by assimilation and fractional crystallization. To sum up, the pink medium-coarse grained monzonitic granite(the early late Paleozoic second invasion granitic body) and Alkali metasomatism Type uranium deposit have close relationships of the space and time and genetic, it is not only uranium metallogenic source of ore-forming materials, but also an important identification marks of uranium prospecting. |
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